Graded devices for use with tubes are known, such devices being disclosed in U.S. Pat. Nos. 1,448,457; 2,479,702; 2,938,562 and 3,200,627. The structures of these patents include fluid conveying mandrels receiveable within the tubes, means for expanding the mandrels to hold the tubing, and die elements against which portions of the tube are flared or otherwise formed by fluid pressure. Many of these expanding devices are customarily used to provide short bulges in tubing for coupling purposes and the like. In addition, they are used to expand tubing to fit fins and other apparatus connected to the outer surface of the tubing.
Several hydraulic chucks have been developed which are suitable for tightly gripping one end of an elongated tube while simultaneously delivering a tube expanding fluid. Among these are U.S. Pat. Nos. 3,505,846; 3,813,751; 3,962,769 and 4,189;162.